Senior Full-Stack .NET Modernization Developer

Xcelo Group; Atlanta (GA); Hybrid; USD 120,000 - 180,000; Full time

Job summary

Xcelo Group in Atlanta, GA seeks a Senior Full-Stack .NET Modernization Developer to lead modernization of legacy ASP.NET apps to .NET 8+, build REST APIs, and enhance React front-ends.

The role requires 10+ years of experience, strong Azure and SQL Server skills, and proven ownership from design through production support in a hybrid work environment. You will design scalable architectures and implement CI/CD in Azure DevOps while collaborating across teams.

Qualifications

• 10+ years of professional software development experience.
• Strong hands-on with C#, ASP.NET MVC, and REST APIs.
• Proven experience modernizing legacy ASP.NET to .NET 6/7/8/10.
• 5+ years of Agile delivery using Scrum or Kanban.
• Experience with Azure DevOps or GitHub and CI/CD pipelines.

Responsibilities

• Modernize legacy ASP.NET applications to modern .NET architectures.
• Design scalable, secure enterprise application solutions.
• Develop and maintain REST APIs for enterprise use.
• Build and enhance React user interfaces within an existing app.
• Own end-to-end delivery from design to production support.

Skills

C#

ASP.NET MVC

REST APIs

React

Agile delivery

Education

Bachelor's degree in Computer Science, Information Technology, or related field

Tools

Azure DevOps

Git

Azure Functions

Azure App Services

SQL Server

T-SQL

Job description

Hi,

We are having immediate requirement on below mentioned JD; Job Title: Senior Full-Stack .NET Modernization Developer

Work Location: Atlanta, GA
Candidate Requirement: Local Atlanta, GA candidates only
Work Mode: Hybrid
Work Auth: Any Visa accepted (No H1 and No Fake Profile)
Experience Required: 10+ years

Role Overview

We are seeking a highly experienced Senior .NET Developer / Application Modernization Engineer to support the modernization of a mission-critical statewide licensing and eligibility platform.

The ideal candidate will have strong hands-on experience modernizing legacy ASP.NET applications to modern .NET 6/7/8/10 , building secure and scalable REST APIs , developing React components , working with Azure cloud services , and managing complex SQL Server environments.

This is not a pure maintenance role. The selected candidate will be expected to take ownership of solutions from design and development through testing, deployment, documentation, and production support .

Required Education

• Bachelor's degree in Computer Science, Information Technology, or a related field

• Equivalent professional experience may be considered

Required Experience

• 10+ years of overall professional software development experience

• Strong hands-on experience with:

  • C#

  • ASP.NET MVC

  • ASP.NET Web API / REST APIs

• Proven experience modernizing production applications from legacy ASP.NET to .NET 6, 7, 8, or 10

• Must have completed real-world application modernization initiatives, not only proof-of-concept work

• 5+ years of Agile delivery experience using Scrum or Kanban

• Experience with Azure DevOps or GitHub

• Strong production troubleshooting and root-cause analysis experience

Core Technical Requirements .NET Application Modernization

• Lead modernization of legacy enterprise applications to modern .NET 8+ / .NET 10

• Design scalable, secure, maintainable application architectures

• Reduce technical debt and improve platform maintainability

• Participate in application architecture and technical design decisions

• Strong understanding of modern .NET application patterns and best practices

REST API Development

• Design, build, and maintain RESTful APIs

• Experience supporting APIs consumed by external systems

• Strong understanding of API contracts, integration patterns, error handling, versioning, and documentation

• Experience building API-first enterprise applications

React / Frontend Development

• Minimum 3 years of React experience

• Must have experience building and enhancing React components within an existing enterprise application

• Strong understanding of:

  • Component-based architecture

  • Client-side rendering (CSR)

  • Server-side rendering (SSR)

  • Modern frontend development patterns

Microsoft Azure

Strong hands-on experience with:

• Azure App Services

• Azure Function Apps

• Application configuration management

• Cloud deployments

• Azure-based application integration

• Deployment and release pipelines

• Azure DevOps CI/CD

SQL Server

Strong production experience with:

• SQL Server

• T-SQL

• Stored procedures

• Query and performance tuning

• Schema changes and migrations

• Data cleanup

• Data migration

• Database troubleshooting

• Data architecture

CI/CD & DevOps

• Develop and maintain CI/CD pipelines using Azure DevOps

• Automate builds, testing, releases, and deployments

• Support configuration and environment management

• Experience with Git-based development workflows

• Strong code review, release management, and deployment practices

Reporting Experience

Minimum 3 years of experience with one or both of the following:

• Power BI

• SSRS

Integration Experience

• Experience integrating third-party services and internal enterprise APIs

• Strong API and middleware integration background

• Experience with middleware platforms such as:

  • Boomi

  • MuleSoft

AI / Azure AI Exposure

Preferred experience with:

• Azure Agentic AI services

• Azure AI integrations

• Microsoft Copilot-related tooling

• Chatbot integrations

• AI-driven features integrated into production applications

Accessibility & Compliance

Preferred experience with:

• ADA / WCAG 2.1 AA accessibility standards

• Government, healthcare, or public-sector applications

• Compliance and auditability requirements

• PII data

• Data security and privacy controls

Domain Experience

Minimum 3 years of experience in one or more of the following environments is preferred:

• Government

• State or public-sector systems

• Healthcare

• Highly regulated enterprise applications

Key Responsibilities

• Modernize legacy ASP.NET applications to modern .NET and Azure-based architectures

• Design scalable and secure enterprise application solutions

• Develop cloud-native applications using Azure services

• Build and enhance React user interfaces

• Develop and maintain enterprise REST APIs

• Own SQL Server performance, migration, and modernization activities

• Create and maintain CI/CD pipelines through Azure DevOps

• Integrate internal and external services

• Develop Power BI and/or SSRS reports

• Support Azure AI, Copilot, chatbot, and Agentic AI integration initiatives

• Conduct code reviews and architecture reviews

• Troubleshoot production issues independently

• Perform root-cause analysis and implement long-term fixes

• Maintain technical documentation, deployment runbooks, and support guides

• Participate in Agile ceremonies and sprint delivery

• Take ownership of assigned solutions from concept through production

Must-Have Skills

10+ Years Experience, Local Atlanta GA, C#, ASP.NET MVC, ASP.NET Web API, .NET 6/7/8/10, Legacy Application Modernization, React, REST APIs, Microsoft Azure, Azure App Services, Azure Functions, Azure DevOps, CI/CD, SQL Server, T-SQL, Stored Procedures, Agile, Git

Preferred Skills

Power BI, SSRS, Azure Agentic AI, Copilot, Chatbots, Boomi, MuleSoft, ADA, WCAG 2.1 AA, PII, Government, Healthcare, Public Sector

Important Candidate Screening Criteria

• Local Atlanta, GA candidates only

• 10+ years of overall experience required

• Strong hands-on legacy ASP.NET to modern .NET migration experience

• Strong Azure + SQL Server + REST API experience

• Hands-on React development within existing enterprise applications

• Must be capable of independently owning technical solutions and resolving production issues